The ever increasing cost of conventional forms of energy has triggered a frenzied search for alternative energy sources. Solar energy, both as a source of heat and as a source of natural illumination, is one of the primary energy sources to which such searches have been directed.
Conventional passive solar energy collection systems take advantage of situations where seasonal and diurnal locations of the sun coincide with both the time and the location of need for solar thermal radiation and do not include facilities to store or transfer it. The advantages of active solar heating systems, which receive, store, and/or transfer the radiant heat of the sun without primary regard to the seasonal and diurnal location of the sun, are realized at considerably greater costs over passive systems.
Existing buildings often are not positioned favorably with respect to the location of the sun, during the winter months when heat is desired or the summer months when solar radiant energy is sought to be avoided, to realize many of the economies of available passive solar energy. Likewise, it is often difficult to build new structures, due to site location constraints, to take advantage of available passive solar energy. Often, buildings which are least able to profit by solar energy collection during the winter months have the largest solar heat gains during the summer months.